Under fluoroscopic guidance, 2-3 cm below the angle of the rib diaphragm in the mid-axillary line was selected as the entry point. After local anesthesia (1% lidocaine, local infiltration anesthesia), the liver was entered by puncture with a fine needle (21G). Note that the puncture is preceded by a 1- to 2-mm breach at the superior border of the rib cage with a sharp knife and subcutaneous expansion with mosquito forceps. The main objectives are to allow stable control of the puncture fine needle’s forward motion without interference from skin resistance; to avoid arterial injury at the lower rib margin; and to reduce resistance for subsequent catheterization over the skin and subcutaneous tissue into the liver. To avoid transcribrodiaphragmatic thoracic puncture, the needle is inserted at rest for breathing (avoiding deep inspiration) or at the end of expiration during fine needle puncture. By entering the biliary tract via thoracic puncture at the angle of the rib diaphragm, negative intrathoracic pressure can aspirate bile into the thoracic cavity along the sinus tract of the drainage tube leading to biliary pleurisy once the drainage tube needs to be removed. Caution should be exercised when selecting the anterior or posterior axillary line for puncture because the angle of the rib diaphragm is lower in this position and the anterior axillary line should be punctured with caution to prevent gallbladder puncture. The most important thing is to determine the presence of interstitial colon on the puncture path. The tip of the puncture needle needs to pass quickly through the hepatic peritoneum into the liver parenchyma during needle entry to avoid cutting the peritoneum on the liver surface. In patients with congestive heart failure or early Budd-Chiari’s syndrome), a cut in the peritoneal surface results in a “skin-on” bleeding episode. The initial approach to the needle is in a parallel line midway between the top of the diaphragm and the base of the liver. If the bile duct is not penetrated in this direction, then a backward or forward puncture is considered. There are two methods to determine whether the puncture needle enters the bile duct: puncture the needle tip up to 2 cm above the hepatic hilar under fluoroscopic guidance, stop fluoroscopy while slowly withdrawing the needle and aspirate with a syringe, and once bile appears in the syringe, inject a small amount of diluted contrast agent under fluoroscopy to observe whether the puncture needle tip is in the bile duct; another method is also to puncture the needle above the hepatic hilar under fluoroscopy and slowly withdraw the needle while slowly pushing in diluted contrast. Once the tip of the needle is in the bile duct during the retraction process, the continuous slow push of contrast will flow slowly along the bile duct and outline the biliary anatomy, and the retraction should be stopped immediately. The first method reduces radiation exposure, and the second method is more sensitive to detecting that the puncture needle tip is in the bile duct. Note: The purpose of injecting more than double the diluted contrast agent is to avoid the thicker contrast agent affecting the subsequent observation of the guidewire alignment; the speed of injecting contrast agent when withdrawing the needle is appropriate to not “stain” the liver parenchyma (the upstairs netizens expressed it as “starry sky” also quite imaginatively). ), although the contrast agent can be absorbed when injected in the liver parenchyma, it also takes time (about 5-10 minutes). Once the puncture needle is confirmed to have entered the bile duct, it is easy for beginners to immediately enter the guide wire and introduce the catheter to complete the drainage operation. However, in practice, the position of the puncture needle into the bile duct is carefully considered for the smooth introduction of the guidewire, to reduce complications and for therapeutic reasons. The experienced person will continue to inject contrast agent (in most cases no more than 5 ml) after confirming the entry of the puncture needle tip into the bile duct until the visualization of the target punctured bile duct. Target punctured bile ducts are defined as ≥ grade 3 bile ducts, puncture needle-bile duct-guide wire isotropy as well as achieving maximum bile drainage. By isotropy, we mean isotropy in stereoscopic space. Normally, we judge the isotropy of the puncture needle-bile duct-fine guidewire in 2D space under fluoroscopy, which is the basis! But this does not guarantee isotropy in 3D space. Therefore, the mind should have spatial imagination and a three-dimensional concept of the anatomy of the bile duct when puncturing the bile duct. The reason why bile duct punctures of ≥3 or higher are performed is because percutaneous biliary puncture under fluoroscopic guidance is blind. A serious complication of this biliary puncture is biliary hemorrhagic fistula, which in the vast majority of cases is caused by the puncture pathway into the bile duct via the portal vein. Mostly due to repeated punctures, side holes of the drainage tube in both portal vein and bile duct and extraction of the drainage tube, portal blood enters the bile duct to different degrees, forming a large number of blood clots, which can affect the function of the drainage tube in the clot in addition to causing bile duct hypertension, and bile duct hypertension + poor drainage induces serious obstructive bile duct infection and even life threatening. The operator has to spend several days (about 3 days of autolysis of the clot in the bile duct) in anxious anticipation of clear bile flow from the drainage duct. In biliary obstruction, the bile ducts of grade ≥3 are dilated, while the normal portal vein accompanying them is already thin at this level. In addition the puncture of the terminal bile duct can preserve a larger number of side holes for adequate drainage at the proximal end of the obstruction in case of internal or external drainage or hilar obstruction, while avoiding the last side hole or multiple side holes in the liver parenchyma outside the bile duct. Imagine that if you perform a level 2 biliary puncture, only perhaps 1 or 2 side holes are retained at the proximal end of the obstruction, and perhaps from time to time the last side hole will move in and out of the bile duct or into the portal vein with the movement of the drainage tube. In fact, achieving a 4-stage biliary puncture is the basis for performing PTCD in the outpatient setting, i.e., the patient goes home after a short observation after the PTCD procedure. Needle-bile duct-guide wire isotropy means that the bile duct being punctured allows the guide wire to enter the deep bile duct smoothly. It is usually easier to advance the guidewire farther into the bile duct by anterior inferior or posterior bile duct puncture. In the case of hilar obstruction, the bile duct that drains more bile should be considered a target punctured bile duct. The technique of target puncture bile duct puncture focuses on identifying the position of the puncture needle relative to the target puncture bile duct. When the above-mentioned initial injection of contrast agent shows the target punctured bile duct, I heard that due to the gravity of the contrast agent the first to be visualized is in the posterior and the later to be visualized is in the anterior. I don’t know if this is correct or not, please judge. Another method I prefer is to first overlap the tip of the puncture needle with the pre-puncture point of the bile duct of the developed target puncture, and rotate the fluoroscopic C-arm slightly to the left (about 20~30°). After adjusting the direction, then rotate the C-arm such that the smaller the distance between the needle tip and the relative movement of the bile duct indicates that the direction of the puncture is closer to the bile duct, and the bile duct wall is visible under fluoroscopy as it moves under the influence of the needle until the needle tip pokes a depression in the bile duct wall on one side indicating that the needle enters the bile duct again.